1. Field of the Invention
The present invention relates to a saddle seat type motor vehicle including a limited slip differential which is preferable for reducing steering effort and the number of components.
2. Description of Background Art
When a motor vehicle turns the turning radii of right and left driving wheels are different in the case of a two-wheel drive vehicle and the wheels rotate at different speeds. Therefore, a limited slip differential is required in order to absorb a difference between the revolution speeds of the driving wheels, i.e. in order to let the wheels rotate at speeds in accordance with their turning radii and distribute appropriate driving torques to the wheels.
This limited slip differential absorbs the difference of revolution speeds of the left and right driving wheels. However, if the left or right driving wheel slips on a road having a small frictional resistance, the other driving wheel has a small driving force, which means a reduced total driving force of the motor vehicle. Especially in the case of a four-wheel drive vehicle or a special vehicle running off-road or the like, a limited slip differential is required between the right and left driving wheels in order to control the difference of revolution speeds of these wheels and secure driving force.
Such a limited slip differential is described in Japanese Patent Publication No. Hei 5-63333, entitled xe2x80x9cDifferential Case for Limited Slip Differentialxe2x80x9d. Referring to FIG. 1 of this publication, the limited slip differential comprises: a drive pinion 2 extending into an axle housing 1; a ring gear 3 engaged with the drive pinion 2; and a differential case 10 coupled to the ring gear 3. The ring gear 3 and differential case 10 are rotatably housed in the axle housing 1. A pinion shaft 31 is attached across the differential case 10 so as to pass therethrough, so that the pinion shaft 31 rotatably supports differential pinions 32 and 33. Both of the differential pinions 32 and 33 engage with side gears 35 and 37, to which drive shafts 8 and 9 are attached. Further, frictional torque generating mechanisms are provided between the inner surface of the differential case 10 and outer surfaces of the side gears 35 and 37.
A saddle seat type motor vehicle such as a buggy used on uneven ground and provided with a limited slip differential is required to have a compact and light body in order to turn in small radii to have improved handling.
Such a limited slip differential installed between the right and left front driving wheels has substantially the same structures for applying driving torque to the drive shafts 8 and 9. It is difficult for the limited slip differential to improve handling, i.e. it does not contribute to a reduction in the steering effort, so that further measures have to be provided in order to reduce the steering effort.
Recently, tires have been designed to have large diameters and widths in order to improve running performance of vehicles used off-road, which means an increase in the steering effort. Therefore, there have been great demands for reducing steering effort.
Further, the foregoing limited slip differential comprises many components which should be assembled in a number of processes. In order to reduce the manufacturing cost of the vehicle, it is necessary to reduce the number of components.
Therefore, the present invention is intended to provide a saddle seat type motor vehicle including a limited slip differential in order to reduce the steering effort and the number of components.
In order to accomplish the foregoing object, the present invention provides a saddle seat type motor vehicle for use off-road or the like and provided with a limited slip differential, which is positioned between right and left front wheels, and distributes to the right and left front wheels driving torques differentiated in accordance with a predetermined ratio when the front wheels rotate at different speeds.
The limited slip differential provides the front wheels with driving torques which are differentiated in accordance with a difference of revolution speeds of these wheels.
The limited slip differential supplies large driving torque to an inner wheel rotating at a low speed compared with an outer wheel rotating at a high speed, which is effective in improving the turning behavior and reducing steering effort.
According to the present invention, the limited slip differential includes a plurality of input side blocks moving around the axis in response to the rotation of a ring gear, two output side cams sandwiching the input side blocks for the purpose of letting the input side blocks relatively slip therebetween, and being capable of independently rotating using frictional force with the input side blocks, and a case for housing the input side blocks and the output side cams.
A plurality of input side blocks are sandwiched between the two input side cams such that the side blocks are capable of slipping relatively therebetween. The input side blocks and output side cams are housed in the case. The input side blocks move round the axis in response to the rotation of the ring gear, so that the output side cams rotate independently due to frictional force generated by the movement of the input side blocks, and driving torque is transmitted to the output side cams from the input side blocks.
It is therefore possible to distribute to the output side cams driving torques which are differentiated at the predetermined ratio in accordance with directions of frictional force varying with relative slippage of the input side blocks and output side cams due to different revolution speeds of the two output side cams.
In addition, the present invention provides for a ring gear which is integral with a part of the case.
The ring gear integral with the case does not require any fastening bolts compared with a case and a ring gear which are separate. This is effective in reducing the number of components, facilitating an assembly process, and lowering manufacturing cost.
Further scope of applicability of the present invention will become apparent from the detailed description given hereinafter. However, it should be understood that the detailed description and specific examples, while indicating preferred embodiments of the invention, are given by way of illustration only, since various changes and modifications within the spirit and scope of the invention will become apparent to those skilled in the art from this detailed description.